There are many ways to make this happen, the easiest would probably be using the GameState to keep track of everything, and spawn where necessary. Honestly, these questions are so open and vague with so many solutions it’s evident you have a lot of work to do before you need to be asking these questions, because once you are at that point, you won’t have trouble working out how to make these things happen.
If you have a more specific question that’s a different matter